96 c220 MAS?
 

Was reading some old threads on c220 probs and saw something about the MAS (relay?). What does it operate and where is it? I saw somewhere where someone was having trouble with their AC and said it was the MAS. My AC isn't working. Also was running great but tonight came to a stop and it started running badly and check engine light came on. Will have code checked tomorrow but was wondering about this MAS thing. Any help is appreciated.

Only engines from 1990-93 with CIS-E injections had MAS relays!
ON your car the A/C operating unit (pushbutton) does all of the work!

hey thanks, I guess thats good news. I notice the EC button on my climate control is lit all the time. Is this a sticky switch not letting the AC come on? Thanks again

EC means economy which is an A/C compressor inhibit. Is the light staying on even when you push the EC button? It should cycle on and off with each push of the button.

if EC stays on it is because you don't have enough refridegerant in the system for the compressor to run. you need to get the A/C system recharged and have the ultraviolet dye injected to see where it's leaking from. after the recharge you'll have to return in a couple of weeks so the location/severity of the leak can be determined.

Yes, the EC light stays on regardless of how many times I push it. It seems to change fan speed some but the light stays on. I had a local mech friend check the compressor and he said it will run if jumped for a second but no power to the pressure switch. Tried putting a little 134a in but the compressor won't come on to take it. Do you think it's the climate control? Thanks for all help.

You'll need to diagnosis both your problems.

The Check Engine Light (CEL) being lit indicates stored and active codes. Those are your first clues in solving your running problems.

Also, your 1996 ACC control panel has the ability to access the HVAC codes. I can't recall the sequence. Common problems are evaporator temp sensor and leaking condensors. Again, before you start throwing parts at something, find the problem.

With your running problems, get the codes before buying a single part. However, it's probably either an ignition problem (coil, wire, etc.) or Air Mass Meter.

The prob with running bad I think is fixed. My mech said there was moisture in one of the plug wires from when the engine was detailed I guess. Anyway he dried it out and it runs fine and no check engine light. Is there a fuse or relay for the compressor that goes thru the climate control unit?